1. Field of the Invention
This invention relates to musical apparatus. In particular, the invention pertains to an automatic composer which automatically composes melody.
2. Description of the Prior Art
Several automatic composers are known which automatically compose a melody. Examples are disclosed in U.S. Pat. Nos. 4,399,731, 4,554,010, WO No. 86/05616 and Japanese patent application laid-open SHO62/187876.
The automatic composer of U.S. Pat. No. 4,399,731 uses trial-and-error method which generates random numbers to compose a melody note pitch succession. Thus, the composer has an infinite space of melody composing but lacks knowledge or art of music composition so that the chance of getting a good melody as too low.
Each automatic composer of U.S. Pat. No. 4,564,010 and WO No. 86/05616 is a melody composer or transformer which transforms a given melody. The melody transformation involves a mathematical operation (mirror transformation of a pitch succession, linear transformation of a two dimensional space of pitch and durational series). With a limited space of the transformation, the composer has only a fixed and mathematical (rather than musical) capability of melody composition. Japanese patent application laid-open 62/187876 discloses a melody composer which utilizes a Markov chain model to generate a pitch succession. The apparatus composes a melody based on a pitch transit ion table indicative of a Markov chain of a pitch succession. The composed melody has a musical style of the pitch transition table. While it can compose a musical melody at a relatively high efficiency, the composer provides a small space of melody composition since the composed melody style is limited.
Common disadvantages of the prior art described above are
(1) no contemplation of musical background or progression (e.g., musical style, structure, chord progression)
(2) no capability of analyzing or evaluating a melody, and thus
(3) low capability of composing a musical melody.
In view of these, an automatic composer has been proposed which aims at human-like (rather than mechanical) music composing, as disclosed in U.S. Pat. Nos. 4,926,737 and 5,099,740 (a division U.S. Pat. No. 4,926,737), each assigned to the present assignee. The automatic composer has a stored knowledge-base of melody which classifies nonharmonic tones by their relationship formed with harmonic tones based on the premise that a melody is a mixed succession of harmonic and nonharmonic tones. The stored knowledge-base of nonharmonic tone classification is used analyze a melody (motive) supplied by a user is also used to compose or synthesize a melody (phrase succession) following the motive. Further, the automatic composer discloses a phrase rhythm generator which generates a rhythm of a phrase by modifying the original rhythm (motive rhythm). The rhythm modification involves inserting and/or deleting note-on timings into or from the original rhythm according to rhythm control data called pulse scale having weights for individual timings in a musical time interval such as a measure. Where it can compose a musical melody reflecting a feature of the motive, the automatic composer has the following disadvantages.
(A) It requires a large amount of data to be processed for musical composition
(B) Thus, the response is slow. When implemented on a computer of limited performance, the automatic composer composes a melody in non-real time.
(C) Limited capability of generating rhythm patterns. It is difficult to make those rhythm patterns having the same note number but different in a subtle way from one another.
(D) The automatic composer requires complicated algorithmic operations to generate a phrase idea (phrase featuring parameters) for developing or modifying the input motive.
(E) Nevertheless, a composed melody often involves unnaturalness peculiar to the algorithm.